Browsing by Author "Oma, Kenton H."

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    Structure-property relations in epoxy metal-ion polymers
    (1977) Oma, Kenton H.; Armeniades, C. D.
    The feasibility of crosslinking a diepoxy (EPON 828 Shell Chemical Company) with paraaminopyridine (PAP) coordinated to various metal-ions was investigated by means of wide angle x-ray diffraction, infrared spectroscopy, and metallographic examination. Insolubility of the metal-ion ligands in EPON 828, resulting from their ionic nature, necessitated the development of a solution polymerization based on acetone. The effect of molecular structure on the internal friction of these polymers was studied using dynamic mechanical measurements at temperatures from 8°K to Tg with a free oscillating inverted torsional pendulum at 1 Hz. Dynamic mechanical properties of a model system were established by studying the chemically and sterically similar, EPON 828-methylene dianaline (MDA) polymer. The y relaxation temperature, intensity, and the modulus defect decreased with stoichiometrically excessive epoxy and the y relaxation intensity increased with excess MDA. As expected, Tg was maximized in a stoichiometric system. A new mechanical relaxation appeared near 275°K for all specimens prepared from acetone solution. The peak may be due to a relaxation of hydroxy ether links which are bound by secondary forces to residual acetone. Attempts to react EPON 828 with Ni(PAP)x:Cl2 directly and from solution were unsuccessful in forming a completely amorphous highly crosslinked polymer system. However, a solution polymerization technique, using acetone as the solvent was developed. This technique resulted in complete reaction of EPON 828 with Co(PAP)2:CI2. The success in this case is attributed to the relatively high solubility of Co(PAP)2 : CI2 in acetone. The metal-ion polymers showed higher glass transition temperatures than EPON 828-MDA, but had lower tensile strengths at room temperature.